The heme sites in various R- and T-state hemoglobins will be modeled using highly congruent model systems, most especially the Fe(picket fence porphyrin)(base) systems. In addition to the parent compounds, we will characterize by single-crystal X-ray diffraction methods compounds of the type Fe(picket fence porphyrin)(base)L, with base equals 2-methyl imidazole (imposing constraints on the movement of the Fe into the porphyrin plane) and base equals 1-methyl imidazole (unconstrained) with L equals O2, CO, NO, F-. The Co analogues of these complexes will be synthesized and characterized structurally. The affinites of model Fe systems for isocyanides, RNC, will be determined and the structures of CO and RNC model systems in which these molecules are forced to tilt relative to the porphyrin plane will be correlated with uptake properties. Models for various Cu-proteins involved in oxygen transport or oxygen utilization will be synthesized and characterized. A catalogue of structural and spectroscopic data on such model systems will be developed as an aid to the characterization of Cu centers in blue-Cu and other Cu proteins. Synthesis and characterization of models for hemocyanin will be attempted.